The present invention relates to channels that encase fuel bundles in the core of a boiling water nuclear reactor (BWR). The invention specifically relates to tools and method to slide a channel over a fuel bundle.
A fuel assembly for the core of a BWR typically includes an array of fuel rods held together by tie plates and spacers, and a channel that forms exterior sidewalls of the assembly. The channel may be embodied as a hollow tube having thin metallic walls and a rectangular cross-section.
The channel slides over an array of fuel rods, tie plates and spacers. The channel usually slides easily over the assembly until a lower edge of the channel reaches the finger springs of the lower tie plate. The finger springs are biased outward and engage the channel, after the channel is fully seated on the assembly of fuel rods, tie plates and spacers. Before the channel is fully seated, a substantial force is required to push the channel over the finger springs attached to the lower tie plate. To push the channel over the fingers springs, it is required to apply a downward force to the channel by, for example, two persons pushing on the upper edge of the channel or by positioning a wooden board on the upper edge of the channel and having two persons on opposite ends of the board push downward on the ends of the board. These conventional methods used to force a channel over an assembly may result in: (1) an injury to the persons pushing down on the channel, (2) an improperly seated channel, (3) debris falling into the fuel bundle assembly, or (4) damage to the fuel bundle assembly. There is a long felt need for a better method and tool for seating a channel on a fuel bundle assembly.